Is there a way to uniformly add texture to a complex mesh without using UV mapping?
What render engine will you be using? Cycles? Blender Internal? OpenGL Viewport/Game Engine?

Yes, for the most part you can, except for real time rendering; for which you probably have little options but to unwrap.

For the other two you could use either one of two methods:


Generated Texture Coordinates - Will fit a 1x1x1 cube of the image to the object using a 3 axis box like projection. You can later adjust repetition by controlling the scale of the image or with a vector mapping node.
Object Texture coordinates Will evenly tile the texture over your object regardless of size. The texture will stretch if the object itself is not evenly scaled. You can also adjust repetition by controlling the size of the image or with a vector mapping node.


For both no unwrapping is necessary, face angles will be used to mask from where the texture will be projected. Be sure to select Box projection mode in your image texture node.